Spelljammer is canonical for FR Edit
References include, but are not limited to:
- Forgotten Realms Campaign Setting actually supports the existance of Spelljammer (and Kara-Tur, Maztica and Al-Qadim). Read the section called The Sea of Night on pages 230-231.
- Elves of Evermeet mentions several spelljamming ships are housed in Evermeet.
- Forgotten Realms Accessory: Gold & Glory mentions Code Helm, Emerald Brotherhood, The Enforcers and The Gauntlet. Four mercenary groups found in Realmspace.
- Dungeon Crawl: Undermountain--Stardock is an adventure that starts in the tunnels below Waterdeep and then takes the players through a portal to one of the Tears of Selûne called Stardock.
- Arcane Age Accessory: Cormanthyr - Empire of the Elves mentions opposition to the Netherese spelljammers by Cormanthyr and the Elven Imperial Navy and also the Elaorman ritual used to create elven crystal spelljamming ships.
- Arcane Age Boxed Set: Netheril - Empire of Magic includes information about the Neteril spelljamming ships and spells to permantly seal crystal spheres and create ships that travel at double spelljamming speed.
According to the text, the tears appeared circa -3500 DR and were observed by the Emperor of Shou Lung. It should be noted that (canonically) Nung Fu became the first Emperor of Shou Lung in -1250 DR, 2,225 years later, during the second age of Shou Lung.
In fact, the first age of Shou Lung began in -2487 DR!
I know that as "original research" it should not be included in the main article, but it seems to me much more likely that the date of formation of the tears is closer to -2500 DR that the cited -3500 DR; the first age of Shou Lung began in -2487 DR, making that the earliest date possible in which a "Shou Lung Emperor" (local king) could exist; furthermore, two years prior, on -2489 DR, the deities of what would become the Mulhorandi pantheon (the "God-Kings") arrived on Toril, which would neatly offer a plausible explanation for the tears' origin.
The one thing I'm absolutely certain of is that, based on the "shou documentation", it could not have possibly been -3500 DR.